This is a good quality lightweight tube. It's quite a bit lighter than standard tubes and saving on rotating mass is twice as advantages as static mass (read that somewhere). I can't speak to puncture resistance but so far so good.

I had an impulse to weigh these tubes along with lightweights from Michelin, Continental, Vittoria and even latex Criteriums. I was surprised to discover that these were slightly lighter than all the rest. The difference in weight is not enough reason to buy these instead, since they were all within 10 grams of each other, but the lower price is.

This 48mm P tube weighed 62 grams 5gm less than advertised. Compared to the 32mmP tube that it replaced that weighed 105 grams... a pretty significant saving for just a $2-3 premium. I'm no racer and I'll probably not notice the difference, but lighter is always better in my book. Can't speak to flat resistance as I've just installed the tube replacing a tube that apparently I damaged during installation as there was two leaks on the inside of the tube. This new tube I installed without the use of tire levers so tube seems to be holding air, so I'm good to go....

I've been cycling well over 40 years and have very rarely had a tube failure that wasn't due to my own ineptitude/carelessness in installation, or, the inevitable random puncture from road debris. I'm experienced, careful, mechanically inclined, and still make a mistake now and then installing them, and we all hit nasty debris without knowing it til we hear the PFFSSSSTT!!. These Cretons that rate tires/tubes based on how often they flat, are just that, Cretons!! They're either being careless in installation, or they're hitting debris, at least 90% of the time. Use talc and get the tube in straight, without folds or kinks, get the stem straight BEFORE inflating and these tubes are as good as any. I used to get even lighter butyl tubes from another retailer but they discontinued them, probably because every time someone got a flat with them, they blamed it on the tube. Lightweight tubes FEEL GREAT! I'd still be using 45 gram butyl tubes with my 180 gram race tires if they were available. These are now my default tubes for most riding.

Many people may not think saving 20 grams makes a difference but it does, OK in the order of a slightly noticeable improvement. The ride quality also improves a little as the thinner rubber is more compliant. Reducing rotating weight at the rim is the not so secret way to making your bike faster and this is a low cost way of making an improvement. The difference in puncture resistance is negligible as the penetration difference is about 0.3 mm between them. Nashbar kills everyone for price on these lite tubes and I have had no quality issues with them.